Thymic necrosis following oral inoculation of mouse thymic virus.

Mouse thymic virus (MTLV;ICTV designation murid herpesvirus 3) infects developing T lymphocytes of neonatal mice, causing thymic necrosis and acute immunosuppression. Infected animals shed virus indefinitely. However, although transmission in nature is presumably by contact and is likely to involve the oral-nasal route, virtually all experimental studies with MTLV have used systemic (intraperitoneal) inoculation. In order to determine whether systemic inoculation causes artifacts in pathogenesis of the infection, effects of intraperitoneal and oral-nasal inoculation were compared in newborn mice. Thymic necrosis occurred with either route of inoculation, although rate of infection was lower with oral inoculation, varying from about 20% to 67%. There were no gross differences in pathogenesis. Orally infected animals seroconverted and shed virus. These data indicate that the apparent lymphotropism of thymic virus, and induction of thymic necrosis, are not dependent on route of inoculation.